Jennifer Garner’s significant other is upset because her former husband, Ben Affleck, is reportedly considering acting in a film alongside her.

According to reports, John Miller, who has been in a long-term relationship with Garner, sees Affleck’s actions as a form of “meddling.”

It has been reported that he suggested Jennifer Garner should establish clear boundaries with her co-parent and even participated in couples therapy with the actress to discuss Ben Affleck’s involvement.

According to reports from Radar Online, Affleck has shown interest in starring in a movie alongside his former spouse Garner, with whom he shares parenting responsibilities for their children – Violet, aged 19, Seraphina [Fin], aged 16, and Samuel, aged 13.

The two previously shared the screen in the 2003 action movie, “Daredevil,” and Affleck is hoping to rekindle their working relationship.

However, Garner’s partner, Miller, is none too pleased with her ex-husband Affleck’s latest professional moves and is said to be “fuming.”

“John has just about had it with Ben’s meddling,” an insider said about Miller, who began dating Garner shortly after she divorced Affleck.

Because of their parenting arrangement and amicable relationship, Affleck’s close bond with Garner has led to some complications in Miller’s relationship with the actress.

Insiders close to the couple previously told the news outlet that they were pushed into couples therapy because of her close ties with Affleck.

Miller also reportedly demanded that Garner establish clear boundaries with her ex-husband.

On a number of occasions, Affleck has been seen showering praise on Garner in interviews. Now, sources believe the actor’s lingering affection will make such a potential work relationship tough to balance for Garner.

“Ben makes it clear how much affection and admiration he still has for Jen as a mom, an actress, and even as a businesswoman,” a source told the outlet. “She’s good at just about everything and continues to be incredibly important to him.”

Despite the possibility of having to face awkward situations with Affleck if they work together, Garner is said not to see it as an issue, as she believes she can clearly set boundaries between them.

However, insiders don’t think Miller would be satisfied with just trusting Garner to do the right thing.

“For Jen, working with Ben’s studio would be a no-brainer. Even if Ben blurs the boundaries between them, she knows where to draw the line,” the source noted, adding, “But that’s likely not enough to keep John happy.”

One of the instances of Affleck praising Garner occurred during his recent GQ cover story. He described Garner as a solid “partner” whom he is grateful to have and emphasized how well they work together.

“I’m really lucky that I have a really good co-parent and partner in Jennifer Garner, the kids’ mom, who’s wonderful and great, and we work together well,” he told the outlet.

The actor also partly attributed the success of their parenting arrangement to how they have safeguarded their lives from the media and ensured that their kids are kept informed about everything they do.

“We used to have a thing, my ex-wife and I, when they would see something on a supermarket stand,” Affleck shared at the time, noting, “we would say, well, ‘You know this isn’t always true because if it were, you would have 15 brothers or sisters or whatever the number of stories is where they said that your mom was pregnant.'”

Beyond Affleck praising Garner, the duo were recently seen engaging in a display of affection during a family outing.

The act involved Affleck casually wrapping his arm around Garner’s waist, which led to speculations that they might be considering getting back together.

However, the rumors were later slammed by sources close to Affleck, who deemed it “ridiculous.”